Method of producing or developing azo dyes



Patenteed July 28, i I

Heirs mirEoinolt man es crrAitLo'rrE amtin womzs; mo,,*oE;1\ Ew'yoEK,@1 I. Y., A ooE-PoRA'rIoN or DELAWARE t METHOD r e eeme oE'f Ev'ELorING Azo DYES 1 Drawing, p ilaa n-fiaatime 11"; 192aseri -r "no. 94,057, ana1 in Germany March 17, 1925; 1

l a The so'called ilitros'amines of the Primary aromatic amines. of the" general? formula RQN=N4OL metal have attained a certain theoretical importance both on'account of: the surprising stability they possess as 'coin pared with the diazon'ium compounds which are very" liable todecomposition, and on ac-'- c'ount-of the particular behaviour or the reactions theyndisplay relationfto the usual azogcomponents; ;;-None of the said Intros-i amines is of'technica'lo-r commercial value withth'e sole exception of the sodium salt islltnown i nthe trade unde'r the denom'ination corresponding to thepnitranilih and which of NitrosamineRed-t "On account "of lack of reactability however, it wasnot' possible heretofore, exceptlyin a'fewcasesgto' utilize the stated sodium compoundffor dye-synthe- I sisimmediately,that is to say, without previously' is'omerl zing the earns to form a"; diazo niumcompoundgfandithese few oaseshave been practised in cloth-printingonlyiand even for this purpose theaddition'al employment of acids," acid salts or othernalkali binding sub stanc'eshas'been found to be indispensable.

If liavediscovered, after much 1 study and research,that I canbri-ng' about, under suit able conditions, the formation of a- "dye even in a decidedly-alkaline medium i Moreover found that the formation of the dy i f going on by far slower than'the couplin'g'of the diazonium compounds, can be efi'ected so as to, take a plain course; I v q 3 I The essential conditions to" be complied with for the purpose are as follows:

( 1)? the necessity, of avoiding excessive concentration of caustic alkali,

the necessity of employing higher temperatures up to to C. f t I E wamplc. 1.,Employment,of the v, antidi- "azo'tate from p-nitranilin (nitro sainine=red) Equivalent amounts of i the 'nit'ro'samine produced as a. unit or in a otthe ia'zo-com'ponents such as 2,6 or 2,8- naphtholsulfonic acid,

2,3',6 naphthol- EB RG, GERMANY, ASSIGNOR T0 GENERAE disulfonic acid,.1 ,2 or 1,4 naphthylaminc-sultonic acid,v resorcin' or m toluylendiamine,

are mixed together and the mixture is-heated to atemperature 'of'90- to 100 C. for some timeuntil it is found that the formation of t the dye "is finished or until the dye C0111- ;pon'ents have disappeared Usually the dyesseparate' in crystalline form during thereactiion. The dye resulting, from nitrosamine and l,8,4,6iamino-naphthol-disul-, ionic acid is distinguished as regards its behaviour against acids and alkalis withrel a' tion to the'ftones of colour produced thereby, fromthe monoazo dye resulting from the and appears to coupling in an acid medium result-iiromor' form by a'coupling, action on the naphthol side;

cording'tto the methods hithertoin use. The

suppositionofa coupling action on the naphthol side supported by the fact that naphthol sulfonic, acids are more readily capable of coupling with nitrosamine than naphthylamine-sulfonic acids. The particulars above mentioned respecting the 1,8,4,

6 -an 1in o-naphthol-disulfonic acid also apply g0 to the corresponding dyes resulting from yand j-acids (2,8,6-and" 2,5,7 amino- 1 naphthol sulfonic acids, respectively) which when coupled with diaz'onium chlorideq'in t the manner hithertoemployed, also Etollow ""adifierent' course of reaction from that which I, Itis known to'persons versed in; the art. thatrthis dye could notjbe unite'd'form ac I they'follow in the process of the present invention, This fact likewise renders the new method valuable in technical application.

The probable course of the. reactions is indicated intthe following equation no 1. yHz i NaCI) SOalla rI'n case of using an rim-component such as B napthol I ensure a tqulck; coupling, 1n

'contradistinction to prior knowledge, by

working at a high temperature and by avoiding as far as possibleany excess of caustic V alkali.

-My improved method is also applicable for developing the dye-stufi or colouring matter immediately 'on the textile 'fibres just as hitherto practiced in the usual dyeing "or padding process by means of acid diazonlum compounds, and this way -1s evidently an advance in the art. If the nitrosamine salt solution is added to the padding bath prior to the padding operation, the

developmentcan be brought about by steams ing. In case of cloth or fabrics which have been subjected to a preliminary dyeingoperation, either a uniform or a partial develop ,ment may be effected, as desired orrequired,

by way of padding or printing with the nitrosamine salt solution. v 1 V li occmtple r@.Producti,0n of para-red on the fibres from the nitrosamineof p-nitran- .ilin-and B-naphthol.

- About one half kilo of a printing aye'cet taining gr of ,B-naphthol (in the form of itsiNa-salt).,'l0 gr. of NaOH dissolved in 100 cc. of water, and the usual additions par:

ticularly of thickening substances, is mixed with a quantity of nitrosamine corresponding to- '20 gr. of. ,p-nitranilin. Aprinting dye thus prepared will be stable and lasting for aperiod of time say twenty four hours.

Immediately before the printing operation commences a mixture is to be added to the printing dyeiwhich mixture is composed "of 50 gr. of'bicarbonate .of sodium and such a quantity of athickening agent or in'crassative that the totalweight of the printing dye will amount to 1kg. Theprinting operation finished the cloth or fabric is subjected to a drying operation, a subsequent steaming operation and a final soaping operation.

The probable course of the reactions is indicated in the following equation :1

In'lieu of bicarbonate also any other suits ablealkali binding or neutralizing agents 1 such as magnesium chloride, calcium chloride.

- or ammonium chloride, may be used for bindmg the surplus of alkali, but it must be taken into account at the same time that two equivalents of NaOH are liberated from ,B-naphthol and nitrosamine sodium, that is one equivalent from either compound, which must be rendered inactive, particularly in case that the development of the para-red is efiected by means of a steaming operation, Whereas in ase of developing by means of ahangmg process the stated amounts of alkali will not be objectionable to the same degree.

In case of developments by meansof nitrosamines which are sensitive to anyexcess of 'alkali,such as the dye-stuff of a p nitro-oanisidin and ,8-naphthol, it is advisable to removethe caustic alkali completely.

The described method can also be carried improved method so that the latterwillbe applicable in quite a large variety of practical cases; At any rate the alkaline nature or condition of thedeveloping fluid will be a noticeable improvement upon the customary acid'diazonium compounds hitherto used in the art, even from the standpoint of the dyer and printer...

It will thusbe seen that-my invention comprises a method of producingazo dyes, which consists in causing an alkali metal compound of a nitrosamine derived :from a primary aromatic amino compound, including substitution products thereof, to react, in the presence, or not, of a textile fabric, with a coupling component at a supernormal tempera- T ture, preferably at about to- 0., in the presence of an inorganic salt, such as sodium bicarbonate or an alkaline earth metal salt,which is capable of reducing the alkalinity of the caustic alkali set free by the reaction. I q s It will be evident that my mast whil t st1ll being adhered to in its main essentials, may be varied and adapted in many ways according to the requirements desired or most suitable under different circumstances. I would therefore have it understood that I do not limit myself to the examples described in detail, but holdmyself at liberty to make such departures therefrom as fairly fall within the spirit and scope of my invention.

" What I ultimatep reaction.

i coupling component atabout 90 to 100 C. in

2? comprises causing analkali metal compound ofa nitrosamine derivedffrom p-nitranilinto 0 Q9 ence of an inorganic salt capable of reducing "6. A process of making azo dyes which 1. A processof vmaking azo dyes which comprises causing an alkali metal compound of a nitrosamine derived from a primary aromatic amino compound to react with a coupling component at'a supernormal temperature up to 100 C. in the presence of an vinorganic salt capable ofreducing the alka linity'of the caustic alkali set free by the] 2. A process of making azo dyes which comprises causing analkali metal compound of a nitrosamine derived from a primary aromatic amino compound to react with a thepresence of aninorganic'salt capable of A i reducing the alkalinity, of the caustic alkali set free by the reaction; A

f 3. A process of making azo dyes which of a nitrosamine derived from a primary arc m atic amino compound to react Witha coupling component at about 90 to 100 C; in the 7 presence of sodium bicarbonate. i I 975 ,.4."A cprocess of making azo dyes which comprises causing anlalkali metal compound react-With a coupling component at a supernormal temperature up to 100C; inthepies- {the alkalinity of the causticalkali set free by the reaction. I I v A process ofmaking azo dyes which comprises causing an alkali metal compound of a 'nitrosamine derived from p-nitranilin to react With a coupling component at about to C. in the presence of an inorganic salt capable of reducing the alkalinity of the caustic alkali set free by the'reaction;

comprises causing an alkali metal compound of a nitrosamine derived from p-nitranilin to react With a coupling component at about 90 to 100 C. in the presence of sodium bicarbonate. I r 0 V a In-testimony whereof I aflix my'si'gnature. c HANS THEODOR' BUCHERER; 

